The Man Who Builds Hearts
Breakthroughs in regenerative medicine have received quite a bit of attention on the web recently, with this particular story making the rounds several times. We linked to it back in March after 60 Minutes did a piece on it, although then (and today) our emphasis is more on Wake Forest University's efforts to grow human tissues and organs than the University of Pittsburgh's use of extracellular matrix to regrow body parts. Both are very exciting lines of research, but it was the latter that caught the attention of the BBC and ultimately the Volokh Conspiracy, who subsequently linked to this piece, wherein a "leading plastic surgeon," apparently after carefully viewing the entire 59-second BBC clip -- possibly more than once! -- declared the entire matter "junk science."
This assessment will no doubt come as a shock to the U. S. Army Institute of Surgical Research, who just awarded $42.5 million to Wake Forest and the University of Pittsburgh, in support of a "massive regenerative medicine project aimed at battlefield injuries." Apparently both of these institutions have been working on a number of "junk science" projects with the Department of Defense over the past few years, and the DOD now sees great potential in treating a wide variety of battlefield injuries, including:
Wound healing without scarring
Limb reconstruction, regeneration or transplantation
Compartment syndrome, a condition related to inflammation after surgery or injury that can lead to increased pressure, impaired blood flow, nerve damage and muscle death.
Here's hoping that this research yields significant relief and healing to patients who have suffered traumatic injuries on the battlefield.
Meanwhile, following up on our original piece on this subject, we recently caught up with Dr. Anthony Atala, the director of the Wake Forest Institute for Regenerative Medicine, and got some more information on his team's efforts to grow human tissues and organs, essentially "replacement parts" for the sick and injured. Here he talks about using inkjet printers to literally "print out" new tissues, and addresses the question of whether his research in regenerative medicine has implications for life extension research.
You've been quoted as saying that it is "just a matter of time" before someone grows a human heart. So let's start with the basic question -- how does one grow a heart? We've read how an artificially grown human bladder was recently implanted into a patient: that it was built using layers of tissue attached to a bladder-shaped scaffolding which eventually dissolved, leaving an intact organ in place. Will a human heart be built by similar means? If so, where do these layers of tissue come from? Are they grown from stem cells?
It’s hard to predict which form of regenerative medicine will eventually be used to help patients with damaged heart muscle. There is the possibility of injecting stem cells that will find their way to the damaged tissue as well as the approach of creating patches of the tissue in the lab that can be used to mend a poorly functioning organ. In many cases, you don’t need an entire new heart to dramatically improve the patient’s life. It may be possible to change a patch of non-functional tissue the same way you change a malfunctioning heart valve. Our interest isn’t specifically to build a human heart, but to make patients better – no matter what strategy is used. Not one technology is going to be best for all patients. I foresee a time when we’ll have a boutique of technologies and will select one based on the patient’s needs. Currently, we are attacking this challenge on multiple fronts, including using a modified ink jet technology to “print” a small two-chamber heart.
In attempting to describe the implications of the research you are doing, I wrote: "If this research leads to the ability to grow new kidneys, patients with severe kidney disease will be able to get replacement kidneys without a healthy person having to give one of theirs up. If this research leads to the ability to grow new hearts, patients with severe heart disease will be able to get replacement hearts without someone having to die." Is that an accurate assessment? And, ultimately, will fully compatible replacement organs grown using these kinds of techniques eliminate the need for organ donation, and all of the logistical, ethical, and immunological difficulties associated with that practice?
There are currently almost 99,000 people on the waiting list for an organ transplant and nowhere near enough donors to meet their needs. Our goal is certainly to develop organs and tissues in the laboratory to help solve this shortage. As you know, we have already created bladders in the laboratory that have been successfully implanted in patients. These are grown from a patient’s own cells, so there were no issues with rejection. Similarly, if organs/tissues are grown from stem cells that are a genetic match to a patient, rejection will not be a problem. It is much too soon to predict whether we’ll be successful growing all organs and whether the need for organ donation can eventually be eliminated.
What is your best estimate for when treatments using the techniques you are developing will be widely available?
Some are already available. In about 50 patients -- a tube made of collagen has been used to repair strictures in the urethra (the tube that releases urine from the body.) Stricture -- which is basically a narrowing of the tube -- can be caused by inflammation or scar tissue from surgery, disease or injury. When surgery is required, the usual procedure is to take tissue grafts from the patient's bladder, rectum, etc. for repair. We have created a collagen-based tube and surgically replaced the restricted part of the urethra. The tube was basically free of cells -- so there were no issues with rejection. These new tubes integrated with the body and became fully functional. In addition, bladders engineered in the laboratory are now being evaluated in clinical trials – the first step to more widespread availability.
In recent years there have been significant developments in the areas of rapid materials fabrication and prototyping via digital technology. There is speculation about 3-D printers that will be able to reproduce virtually any physical object. In using a jet printer to literally "print out" sheets of cells which can become multiple layers of replacement muscle tissue or an entire organ, it seems that you are leveraging these rapid replication techniques for regenerative medicine. Where does this fusion of biological, digital, and materials technology lead us? Will we have a machine that takes in a few sample cells on one end and outputs a healthy new heart or kidney on the other?
You are correct that we are using modified ink-jet technology to “print” tissues and organs. Because the inkjet printer can deliver multiple cell types at a time, and put them in very precise positions, it has the potential to build organs that are composed of many different cells and tissues in a completely novel way. We have utilized inkjet printing technology to build heart, bone, and blood vessel tissues. Currently, in a project for the military, we are working to develop a prototype printer that can “print” skin directly on a burn wound. The technology is remarkable and we look forward to discovering what it can help us accomplish.
Looking ahead, do you have any comments on the implications of this research for extending healthy human life span? Will we be able to maintain our bodies for long periods of time the way we currently maintain vintage automobiles -- replacing worn and broken parts with new and viable ones? Is regenerative medicine the key to longevity?
I do foresee a time when organs will be available off-the-shelf, ready to “plug in” and replace injured or diseased organs. Of course, the primary goal of our work is to help improve the quality of patient’s lives. As far as extending the normal lifespan, regenerative medicine has the potential to help individual patients with diseased organs live longer, but we have to keep in mind that normal aging is a process that affects the entire body.
For a look at some more exciting medical research taking place at Wake Forest University, see our interview with Dr. Zheng Cui, who is developing cancer treatments using the human immune system.